Key to the Families.
Reading edition
PAGE
Leaves linear or scale-like. Pinaceæ 19
Leaves not as above.
A. Leaves compound.
Leaves palmately compound. Æsculaceæ 251
Leaves without an odd leaflet at the end. Cæsalpinaceæ 226
Leaves with an odd leaflet at the end.
Leaves alternate.
Leaflets toothed all around. Juglandaceæ 52
Leaflets entire, or with 1-4 teeth near the base.
Trees with thorns, leaflets entire, generally less than 4 cm. (11/2 inches) long. Fabaceæ 233
Trees without thorns, leaflets entire or with 1-4 teeth near the base, generally longer than 4 cm. (11/2 inches). Simarubaceæ 237
Leaves opposite.
Leaflets 3-5, fruit in pairs. Aceraceæ 239
Leaflets 5-11, fruit single. Oleaceæ 267
A. Leaves simple.
Leaves opposite or whorled.
Petioles more than 4 cm. (11/2 inches) long.
Blades palmately 3-5 lobed. Aceraceæ 239
Blades entire or with 1 or 2 lateral lobes. Bignoniaceæ 284
Petioles less than 4 cm. (11/2 inches) long.
Flowers 4-parted, stone of fruit round. Cornaceæ 259
Flowers 5-parted, stone of fruit flattened. Caprifoliaceæ 288
Leaves alternate.
B. Leaves entire.
Trees with thorns and a milky sap. Maclura in Moraceæ 155
Trees without thorns, sap not milky.
Leaves 3-5 nerved at the base.
Leaves 3-nerved at the base. Celtis in Ulmaceæ 146
Leaves 5-nerved at the base. Cercis in Cæsalpinaceæ 227
Leaves with 1 primary nerve.
Leaves usually more than 1.5 dm. (6 inches) long, flowers solitary.
Flowers appearing before or with the leaves. Anonaceæ 161
Flowers appearing after the leaves. Magnoliaceæ 155
Leaves less than 1.5 dm. (6 inches) long, flowers in clusters.
Bark and leaves aromatic. Lauraceæ 163
Bark and leaves not aromatic.
Fruit dry, an acorn. Quercus imbricaria in Fagaceæ 119
Fruit fleshy.
Fruit with one seed, stone cylindrical. Nyssa in Cornaceæ 259
Fruit with more than one seed, rarely one, seeds flat. Ebenaceæ 265
B. Leaves finely serrate, coarsely toothed or lobed.
C. Leaves with one primary vein.
Bark and leaves aromatic. Lauraceæ 163
Bark and leaves not aromatic.
Staminate and pistillate flowers and fruit in catkins.
Scales of winter buds 2, ovary many-seeded, seeds with a tuft of hairs at the summit. Salix in Salicaceæ 34
Scales of winter buds more than 2, ovary 1-seeded, seeds without a tuft of hairs at the summit. Betulaceæ 78
Staminate and pistillate flowers and fruit not in catkins.
Fruit dry.
Fruit a samara. Ulmus in Ulmaceæ 137
Fruit not a samara.
Bark smooth; fruit spiny. Fagaceæ 92
Bark furrowed; fruit a smooth capsule. Ericaceæ 263
Fruit fleshy.
Flowers more than 8 mm. (1/3 inch) broad, fruit edible, apple-like.
Trees mostly with thorns, fruit with remnant of calyx at apex of fruit, normally with more than 1 seed. Malaceæ 171
Trees without thorns, fruit with no remnant of calyx at the apex, fruit a 1-seeded edible drupe. Amygdalaceæ 216
Flowers less than 8 mm. (1/3 inch) across, fruit a non-edible drupe. Cornaceæ 259
C. Leaves with more than 1 primary vein.
Staminate and pistillate flowers in catkins.
Fruit dry. Populus in Salicaceæ 45
Fruit fleshy. Morus in Moraceæ 151
Staminate and pistillate flowers not in catkins.
Pistillate and staminate flowers separate.
Leaves 3-nerved at the base, fruit a 1-seeded drupe. Celtis in Ulmaceæ 146
Leaves 5-nerved at the base, fruit a head of carpels or achenes.
Bark fissured, not peeling off in flakes, leaves aromatic. Altingiaceæ 166
Bark peeling off in flakes, leaves not aromatic. Platanaceæ 168
Pistillate and staminate flowers in one.
Fruit dry. Tiliaceæ 255
Fruit fleshy. Malaceæ 171